Biochemical, functional, and pharmacological characterization of AT-56, an orally active and selective inhibitor of lipocalin-type prostaglandin D synthase

J Biol Chem. 2009 Mar 20;284(12):7623-30. doi: 10.1074/jbc.M808593200. Epub 2009 Jan 8.

Abstract

We report here that 4-dibenzo[a,d]cyclohepten-5-ylidene-1-[4-(2H-tetrazol-5-yl)-butyl]-piperidine (AT-56) is an orally active and selective inhibitor of lipocalin-type prostaglandin (PG) D synthase (L-PGDS). AT-56 inhibited human and mouse L-PGDSs in a concentration (3-250 microm)-dependent manner but did not affect the activities of hematopoietic PGD synthase (H-PGDS), cyclooxygenase-1 and -2, and microsomal PGE synthase-1. AT-56 inhibited the L-PGDS activity in a competitive manner against the substrate PGH(2) (K(m) = 14 microm) with a K(i) value of 75 microm but did not inhibit the binding of 13-cis-retinoic acid, a nonsubstrate lipophilic ligand, to L-PGDS. NMR titration analysis revealed that AT-56 occupied the catalytic pocket, but not the retinoid-binding pocket, of L-PGDS. AT-56 inhibited the production of PGD(2) by L-PGDS-expressing human TE-671 cells after stimulation with Ca(2+) ionophore (5 microm A23187) with an IC(50) value of about 3 microm without affecting their production of PGE(2) and PGF(2alpha) but had no effect on the PGD(2) production by H-PGDS-expressing human megakaryocytes. Orally administered AT-56 (<30 mg/kg body weight) decreased the PGD(2) production to 40% in the brain of H-PGDS-deficient mice after a stab wound injury in a dose-dependent manner without affecting the production of PGE(2) and PGF(2alpha) and also suppressed the accumulation of eosinophils and monocytes in the bronco-alveolar lavage fluid from the antigen-induced lung inflammation model of human L-PGDS-transgenic mice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Animals
  • Calcimycin / pharmacology
  • Cyclooxygenase 1 / genetics
  • Cyclooxygenase 1 / metabolism
  • Cyclooxygenase 2 / genetics
  • Cyclooxygenase 2 / metabolism
  • Dinoprost / biosynthesis
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Drug Evaluation, Preclinical
  • Enzyme Inhibitors / pharmacology*
  • Eosinophils / enzymology
  • Humans
  • Intramolecular Oxidoreductases / antagonists & inhibitors*
  • Intramolecular Oxidoreductases / genetics
  • Intramolecular Oxidoreductases / metabolism*
  • Ionophores / pharmacology
  • Lipocalins / antagonists & inhibitors*
  • Lipocalins / genetics
  • Lipocalins / metabolism*
  • Male
  • Megakaryocytes / enzymology
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Mice
  • Mice, Knockout
  • Monocytes / enzymology
  • Pneumonia / drug therapy
  • Pneumonia / enzymology*
  • Pneumonia / metabolism
  • Prostaglandin D2 / biosynthesis
  • Wound Healing / drug effects*
  • Wounds, Stab / drug therapy
  • Wounds, Stab / enzymology*
  • Wounds, Stab / genetics

Substances

  • Enzyme Inhibitors
  • Ionophores
  • Lipocalins
  • Membrane Proteins
  • Calcimycin
  • Dinoprost
  • Ptgs2 protein, mouse
  • Cyclooxygenase 1
  • Cyclooxygenase 2
  • PTGS1 protein, human
  • PTGS2 protein, human
  • Ptgs1 protein, mouse
  • Intramolecular Oxidoreductases
  • prostaglandin R2 D-isomerase
  • Prostaglandin D2